Message-Id: <20190610092945.6330-4-amergnat@baylibre.com>
Date:   Mon, 10 Jun 2019 11:29:45 +0200
From:   Alexandre Mergnat <amergnat@...libre.com>
To:     robh+dt@...nel.org, mark.rutland@....com, jic23@...nel.org
Cc:     linux-kernel@...r.kernel.org, linux-iio@...r.kernel.org,
        baylibre-upstreaming@...ups.io, dmitry.torokhov@...il.com,
        linux-input@...r.kernel.org,
        Alexandre Mergnat <amergnat@...libre.com>
Subject: [PATCH v3 3/3] iio: Add PAT9125 optical tracker sensor

This adds support for PixArt Imaging’s miniature low power optical
navigation chip using LASER light source enabling digital surface tracking.

Feature and datasheet: [0]

This IIO driver allows to read delta or relative position on X and Y axis:
  - The position relative to where the system started can be taken through
  punctual "read_raw" which will issue a read in the device registers to
  get the delta between last/current read and return the addition of all
  the deltas.
  - The delta can be retrieved using triggered buffer subscription
  (i.e. iio_readdev). The buffer payload is:
    |32 bits delta X|32 bits delta Y|timestamp|.

The possible I2C addresses are 0x73, 0x75 and 0x79.

X and Y axis CPI resolution can be get/set independently through IIO_SCALE.
The range value is 0-255 which means:
  - 0 to ~1,275 Counts Per Inch on flat surface.
  - 0 to ~630 Counts Per Rev on 1.0mm diameter STS shaft at 1.0mm distance.
More details on the datasheet.

The "position" directory is added to contain drivers which can provide
position data.

Signed-off-by: Alexandre Mergnat <amergnat@...libre.com>

[0]: http://www.pixart.com/products-detail/72/PAT9125EL-TKIT___TKMT

Signed-off-by: Alexandre Mergnat <amergnat@...libre.com>
---
 drivers/iio/Kconfig            |   1 +
 drivers/iio/Makefile           |   1 +
 drivers/iio/position/Kconfig   |  18 ++
 drivers/iio/position/Makefile  |   6 +
 drivers/iio/position/pat9125.c | 499 +++++++++++++++++++++++++++++++++
 5 files changed, 525 insertions(+)
 create mode 100644 drivers/iio/position/Kconfig
 create mode 100644 drivers/iio/position/Makefile
 create mode 100644 drivers/iio/position/pat9125.c

diff --git a/drivers/iio/Kconfig b/drivers/iio/Kconfig
index 1d736a4952ab..23d9780640e7 100644
--- a/drivers/iio/Kconfig
+++ b/drivers/iio/Kconfig
@@ -85,6 +85,7 @@ source "drivers/iio/light/Kconfig"
 source "drivers/iio/magnetometer/Kconfig"
 source "drivers/iio/multiplexer/Kconfig"
 source "drivers/iio/orientation/Kconfig"
+source "drivers/iio/position/Kconfig"
 if IIO_TRIGGER
    source "drivers/iio/trigger/Kconfig"
 endif #IIO_TRIGGER
diff --git a/drivers/iio/Makefile b/drivers/iio/Makefile
index bff682ad1cfb..1712011c0f4a 100644
--- a/drivers/iio/Makefile
+++ b/drivers/iio/Makefile
@@ -31,6 +31,7 @@ obj-y += light/
 obj-y += magnetometer/
 obj-y += multiplexer/
 obj-y += orientation/
+obj-y += position/
 obj-y += potentiometer/
 obj-y += potentiostat/
 obj-y += pressure/
diff --git a/drivers/iio/position/Kconfig b/drivers/iio/position/Kconfig
new file mode 100644
index 000000000000..1cf28896511c
--- /dev/null
+++ b/drivers/iio/position/Kconfig
@@ -0,0 +1,18 @@
+#
+# Optical tracker sensors
+#
+# When adding new entries keep the list in alphabetical order
+
+menu "Optical tracker sensors"
+
+config PAT9125
+	tristate "Optical tracker PAT9125 I2C driver"
+	depends on I2C
+	select IIO_BUFFER
+	help
+	  Say yes here to build support for PAT9125 optical tracker
+	  sensors.
+
+          To compile this driver as a module, say M here: the module will
+          be called pat9125.
+endmenu
diff --git a/drivers/iio/position/Makefile b/drivers/iio/position/Makefile
new file mode 100644
index 000000000000..cf294917ae2c
--- /dev/null
+++ b/drivers/iio/position/Makefile
@@ -0,0 +1,6 @@
+#
+# Makefile for industrial I/O Optical tracker sensor drivers
+#
+
+# When adding new entries keep the list in alphabetical order
+obj-$(CONFIG_PAT9125) += pat9125.o
diff --git a/drivers/iio/position/pat9125.c b/drivers/iio/position/pat9125.c
new file mode 100644
index 000000000000..22bf729bec9b
--- /dev/null
+++ b/drivers/iio/position/pat9125.c
@@ -0,0 +1,499 @@
+// SPDX-License-Identifier: (GPL-2.0)
+/*
+ * Copyright (C) 2019 BayLibre, SAS
+ * Author: Alexandre Mergnat <amergnat@...libre.com>
+ */
+
+#include <linux/bitops.h>
+#include <linux/delay.h>
+#include <linux/interrupt.h>
+#include <linux/i2c.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/iio/events.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/trigger.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_buffer.h>
+#include <linux/iio/kfifo_buf.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+
+/* I2C Address function to ID pin*/
+#define PAT9125_I2C_ADDR_HI		0x73
+#define PAT9125_I2C_ADDR_LO		0x75
+#define PAT9125_I2C_ADDR_NC		0x79
+
+/* Registers */
+#define PAT9125_PRD_ID1_REG		0x00
+#define PAT9125_PRD_ID2_REG		0x01
+#define PAT9125_MOTION_STATUS_REG	0x02
+#define PAT9125_DELTA_X_LO_REG		0x03
+#define PAT9125_DELTA_Y_LO_REG		0x04
+#define PAT9125_OP_MODE_REG		0x05
+#define PAT9125_CONFIG_REG		0x06
+#define PAT9125_WRITE_PROTEC_REG	0x09
+#define PAT9125_SLEEP1_REG		0x0A
+#define PAT9125_SLEEP2_REG		0x0B
+#define PAT9125_RES_X_REG		0x0D
+#define PAT9125_RES_Y_REG		0x0E
+#define PAT9125_DELTA_XY_HI_REG		0x12
+#define PAT9125_SHUTER_REG		0x14
+#define PAT9125_FRAME_AVG_REG		0x17
+#define PAT9125_ORIENTATION_REG		0x19
+
+/* Bits */
+#define PAT9125_VALID_MOTION_DATA_BIT	BIT(7)
+#define PAT9125_RESET_BIT		BIT(7)
+
+/* Registers' values */
+#define PAT9125_SENSOR_ID_VAL			0x31
+#define PAT9125_DISABLE_WRITE_PROTECT_VAL	0x5A
+#define PAT9125_ENABLE_WRITE_PROTECT_VAL	0x00
+
+/* Default Value of sampled value size */
+#define PAT9125_SAMPLED_VAL_BIT_SIZE		12
+
+struct pat9125_data {
+	struct regmap *regmap;
+	struct iio_trigger *indio_trig;	/* Motion detection */
+	s32 delta_x;
+	s32 delta_y;
+	s32 position_x;
+	s32 position_y;
+	bool sampling;
+};
+
+static const struct iio_chan_spec pat9125_channels[] = {
+	{
+		.type = IIO_DISTANCE,
+		.modified = 1,
+		.channel2 = IIO_MOD_X,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+			BIT(IIO_CHAN_INFO_SCALE),
+		.scan_index = 0,
+		.scan_type = {
+			.sign = 's',
+			.realbits = 32,
+			.storagebits = 32,
+			.endianness = IIO_CPU,
+		},
+	},
+	{
+		.type = IIO_DISTANCE,
+		.modified = 1,
+		.channel2 = IIO_MOD_Y,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+			BIT(IIO_CHAN_INFO_SCALE),
+		.scan_index = 1,
+		.scan_type = {
+			.sign = 's',
+			.realbits = 32,
+			.storagebits = 32,
+			.endianness = IIO_CPU,
+		},
+	},
+	IIO_CHAN_SOFT_TIMESTAMP(2),
+};
+
+/**
+ * pat9125_write_pretected_reg() - Write value in protected register.
+ *
+ * @regmap: Pointer to I2C register map.
+ * @reg_addr: Register address.
+ * @reg_value: Value to be write in register.
+ *
+ * A value of zero will be returned on success, a negative errno will
+ * be returned in error cases.
+ */
+static int pat9125_write_pretected_reg(struct iio_dev *indio_dev,
+	u8 reg_addr, u8 reg_value)
+{
+	struct pat9125_data *data = iio_priv(indio_dev);
+	int ret;
+
+	ret = regmap_write(data->regmap,
+			 PAT9125_WRITE_PROTEC_REG,
+			 PAT9125_DISABLE_WRITE_PROTECT_VAL);
+	if (ret < 0) {
+		dev_err(indio_dev->dev.parent, "register 0x%x access failed %d\n",
+			PAT9125_WRITE_PROTEC_REG, ret);
+		return ret;
+	}
+
+	ret = regmap_write(data->regmap, reg_addr, reg_value);
+	if (ret < 0) {
+		dev_err(indio_dev->dev.parent, "register 0x%x access failed %d\n",
+			reg_addr, ret);
+		return ret;
+	}
+
+	ret = regmap_write(data->regmap,
+			 PAT9125_WRITE_PROTEC_REG,
+			 PAT9125_ENABLE_WRITE_PROTECT_VAL);
+	if (ret < 0) {
+		dev_err(indio_dev->dev.parent, "register 0x%x access failed %d\n",
+			PAT9125_WRITE_PROTEC_REG, ret);
+		return ret;
+	}
+	return 0;
+}
+/**
+ * pat9125_read_delta() - Read delta value, update delta & position data.
+ *
+ * @data: Driver's data structure.
+ *
+ * A value of zero will be returned on success, a negative errno will
+ * be returned in error cases.
+ */
+static int pat9125_read_delta(struct pat9125_data *data)
+{
+	struct regmap *regmap = data->regmap;
+	int status = 0;
+	int val_x = 0;
+	int val_y = 0;
+	int val_high_nibbles = 0;
+	int ret;
+
+	ret = regmap_read(regmap, PAT9125_MOTION_STATUS_REG, &status);
+	if (ret < 0)
+		return ret;
+
+	/* Check if motion is detected */
+	if (status & PAT9125_VALID_MOTION_DATA_BIT) {
+		ret = regmap_read(regmap, PAT9125_DELTA_X_LO_REG, &val_x);
+		if (ret < 0)
+			return ret;
+
+		ret = regmap_read(regmap, PAT9125_DELTA_Y_LO_REG, &val_y);
+		if (ret < 0)
+			return ret;
+
+		ret = regmap_read(regmap, PAT9125_DELTA_XY_HI_REG,
+			&val_high_nibbles);
+		if (ret < 0)
+			return ret;
+
+		val_x |= (val_high_nibbles << 4) & 0xF00;
+		val_y |= (val_high_nibbles << 8) & 0xF00;
+		val_x = sign_extend32(val_x,
+			PAT9125_SAMPLED_VAL_BIT_SIZE - 1);
+		val_y = sign_extend32(val_y,
+			PAT9125_SAMPLED_VAL_BIT_SIZE - 1);
+		data->position_x += val_x;
+		data->position_y += val_y;
+		data->delta_x = val_x;
+		data->delta_y = val_y;
+	}
+	return 0;
+}
+
+/**
+ * pat9125_read_raw() - Sample and return the value(s)
+ * function to the associated channel info enum.
+ **/
+static int pat9125_read_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan,
+			    int *val, int *val2, long mask)
+{
+	struct pat9125_data *data = iio_priv(indio_dev);
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		ret = pat9125_read_delta(data);
+		if (ret)
+			return ret;
+		switch (chan->channel2) {
+		case IIO_MOD_X:
+			*val = data->position_x;
+			return IIO_VAL_INT;
+		case IIO_MOD_Y:
+			*val = data->position_y;
+			return IIO_VAL_INT;
+		default:
+			return -EINVAL;
+		}
+	case IIO_CHAN_INFO_SCALE:
+		switch (chan->channel2) {
+		case IIO_MOD_X:
+			ret = regmap_read(data->regmap, PAT9125_RES_X_REG, val);
+			if (ret)
+				return ret;
+			else
+				return IIO_VAL_INT;
+		case IIO_MOD_Y:
+			ret = regmap_read(data->regmap, PAT9125_RES_Y_REG, val);
+			if (ret)
+				return ret;
+			else
+				return IIO_VAL_INT;
+		default:
+			return -EINVAL;
+		}
+	default:
+		return -EINVAL;
+	}
+}
+
+/**
+ * pat9125_write_raw() - Write the value(s)
+ * function to the associated channel info enum.
+ **/
+static int pat9125_write_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan, int val,
+			     int val2, long mask)
+{
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_SCALE:
+		switch (chan->channel2) {
+		case IIO_MOD_X:
+			ret = pat9125_write_pretected_reg(indio_dev,
+				PAT9125_RES_X_REG, val);
+			return ret;
+		case IIO_MOD_Y:
+			ret = pat9125_write_pretected_reg(indio_dev,
+				PAT9125_RES_Y_REG, val);
+			return ret;
+		default:
+			return -EINVAL;
+		}
+	default:
+		return -EINVAL;
+	}
+}
+
+static irqreturn_t pat9125_threaded_trigger_handler(int irq, void *p)
+{
+	struct iio_poll_func *pf = p;
+	struct iio_dev *indio_dev = pf->indio_dev;
+	struct pat9125_data *data = iio_priv(indio_dev);
+	u8 buf[16]; /* Payload: Delta_X (4) | Delta_Y (4) | Timestamp (8) */
+	int ret;
+	s64 timestamp;
+
+	data->sampling = true;
+	ret = pat9125_read_delta(data);
+	if (ret) {
+		dev_err(indio_dev->dev.parent, "Read delta failed %d\n", ret);
+		return IRQ_NONE;
+	}
+	timestamp = iio_get_time_ns(indio_dev);
+	*((s32 *)&buf[0]) = data->delta_x;
+	*((s32 *)&buf[sizeof(s32)]) = data->delta_y;
+	data->delta_x = 0;
+	data->delta_y = 0;
+	iio_push_to_buffers_with_timestamp(indio_dev, buf, timestamp);
+	iio_trigger_notify_done(indio_dev->trig);
+	return IRQ_HANDLED;
+}
+
+/**
+ * pat9125_threaded_event_handler() - Threaded motion detection event handler
+ * @irq: The irq being handled.
+ * @private: struct iio_device pointer for the device.
+ */
+static irqreturn_t pat9125_threaded_event_handler(int irq, void *private)
+{
+	struct iio_dev *indio_dev = private;
+	struct pat9125_data *data = iio_priv(indio_dev);
+
+	iio_trigger_poll_chained(data->indio_trig);
+	return IRQ_HANDLED;
+}
+
+static int pat9125_buffer_postenable(struct iio_dev *indio_dev)
+{
+	struct pat9125_data *data = iio_priv(indio_dev);
+	int ret = 0;
+
+	ret = iio_triggered_buffer_postenable(indio_dev);
+	if (ret)
+		return ret;
+	/* Release interrupt pin on the device */
+	return pat9125_read_delta(data);
+}
+
+static const struct iio_buffer_setup_ops pat9125_buffer_ops = {
+	.postenable = pat9125_buffer_postenable,
+	.predisable = iio_triggered_buffer_predisable,
+};
+
+
+static const struct regmap_config pat9125_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+};
+
+static const struct iio_info pat9125_info = {
+	.read_raw = pat9125_read_raw,
+	.write_raw = pat9125_write_raw,
+};
+
+/*
+ * To detect if a new value is available, register status is checked. This
+ * method is safer than using a flag on GPIO IRQ to track event while sampling
+ * because falling edge is missed when device trig just after a read reg value
+ * (that happen for fast motions or high CPI setting).
+ *
+ * Note: To avoid infinite loop in "iio_trigger_notify_done" when it si not in
+ * buffer mode and kernel warning due to nested IRQ thread,
+ * this function must return 0.
+ */
+static int pat9125_trig_try_reenable(struct iio_trigger *trig)
+{
+	struct pat9125_data *data = iio_trigger_get_drvdata(trig);
+	struct regmap *regmap = data->regmap;
+	int status = 0;
+
+	if (data->sampling) {
+		regmap_read(regmap, PAT9125_MOTION_STATUS_REG, &status);
+		if (status & PAT9125_VALID_MOTION_DATA_BIT) {
+			data->sampling = false;
+			iio_trigger_poll_chained(data->indio_trig);
+			return 0;
+		}
+	}
+	data->sampling = false;
+	return 0;
+}
+
+static const struct iio_trigger_ops pat9125_trigger_ops = {
+	.try_reenable = pat9125_trig_try_reenable,
+};
+
+static int pat9125_probe(struct i2c_client *client,
+			 const struct i2c_device_id *id)
+{
+	struct pat9125_data *data;
+	struct iio_dev *indio_dev;
+	int ret, sensor_pid;
+
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
+	if (!indio_dev) {
+		dev_err(&client->dev, "IIO device allocation failed\n");
+		return -ENOMEM;
+	}
+
+	data = iio_priv(indio_dev);
+	indio_dev->dev.parent = &client->dev;
+	indio_dev->name = id->name;
+	indio_dev->channels = pat9125_channels;
+	indio_dev->num_channels = ARRAY_SIZE(pat9125_channels);
+	indio_dev->info = &pat9125_info;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+
+	ret = devm_iio_triggered_buffer_setup(&client->dev, indio_dev, NULL,
+		pat9125_threaded_trigger_handler, &pat9125_buffer_ops);
+	if (ret) {
+		dev_err(&client->dev, "unable to setup triggered buffer\n");
+		return ret;
+	}
+
+	data->indio_trig = devm_iio_trigger_alloc(&client->dev, "%s-dev%d",
+		indio_dev->name, indio_dev->id);
+	if (!data->indio_trig)
+		return -ENOMEM;
+	data->indio_trig->dev.parent = &client->dev;
+	data->indio_trig->ops = &pat9125_trigger_ops;
+	iio_trigger_set_drvdata(data->indio_trig, data);
+	ret = devm_iio_trigger_register(&client->dev, data->indio_trig);
+	if (ret) {
+		dev_err(&client->dev, "unable to register trigger\n");
+		return ret;
+	}
+
+	data->regmap = devm_regmap_init_i2c(client, &pat9125_regmap_config);
+	if (IS_ERR(data->regmap)) {
+		dev_err(&client->dev, "regmap init failed %ld\n",
+			PTR_ERR(data->regmap));
+		return PTR_ERR(data->regmap);
+	}
+
+	/* Check device ID */
+	ret = regmap_read(data->regmap, PAT9125_PRD_ID1_REG, &sensor_pid);
+	if (ret < 0) {
+		dev_err(&client->dev, "register 0x%x access failed %d\n",
+			PAT9125_PRD_ID1_REG, ret);
+		return ret;
+	}
+	if (sensor_pid != PAT9125_SENSOR_ID_VAL)
+		return -ENODEV;
+
+	/* Switch to bank0 (Magic number)*/
+	ret = regmap_write(data->regmap, 0x7F, 0x00);
+	if (ret < 0) {
+		dev_err(indio_dev->dev.parent, "register 0x%x access failed %d\n",
+			0x7F, ret);
+		return ret;
+	}
+
+	/* Software reset */
+	ret = regmap_write_bits(data->regmap,
+			      PAT9125_CONFIG_REG,
+			      PAT9125_RESET_BIT,
+			      1);
+	if (ret < 0) {
+		dev_err(&client->dev, "register 0x%x access failed %d\n",
+			PAT9125_CONFIG_REG, ret);
+		return ret;
+	}
+
+	msleep(20);
+
+	/* Init GPIO IRQ */
+	if (client->irq) {
+		ret = devm_request_threaded_irq(&client->dev,
+			client->irq,
+			NULL,
+			pat9125_threaded_event_handler,
+			IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
+			"pat9125",
+			indio_dev);
+		if (ret) {
+			dev_err(&client->dev, "GPIO IRQ init failed\n");
+			return ret;
+		}
+	}
+
+	ret = devm_iio_device_register(&client->dev, indio_dev);
+	if (ret) {
+		dev_err(&client->dev, "IIO device register failed\n");
+		return ret;
+	}
+
+	i2c_set_clientdata(client, indio_dev);
+	return 0;
+}
+
+static const struct i2c_device_id pat9125_id[] = {
+	{ "pat9125", 0 },
+	{}
+};
+MODULE_DEVICE_TABLE(i2c, pat9125_id);
+
+static const unsigned short normal_i2c[] = {
+	PAT9125_I2C_ADDR_HI,
+	PAT9125_I2C_ADDR_LO,
+	PAT9125_I2C_ADDR_NC,
+	I2C_CLIENT_END
+};
+
+static struct i2c_driver pat9125_driver = {
+	.driver = {
+		.name = "pat9125",
+	},
+	.probe = pat9125_probe,
+	.address_list = normal_i2c,
+	.id_table = pat9125_id,
+};
+
+module_i2c_driver(pat9125_driver);
+
+MODULE_AUTHOR("Alexandre Mergnat <amergnat@...libre.com>");
+MODULE_DESCRIPTION("Optical Tracking sensor");
+MODULE_LICENSE("GPL");
-- 
2.17.1

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